ABSTRACT The epithelial barrier presents a significant obstacle to the delivery of macromolecules in the size range of 20 - 150 kDa. In particular, the tight junctional complex, which links adjacent cells and occludes the paracellular space, presents a significant obstacle to delivery of macromolecules. To improve the transport of macromolecular biologics across epithelia, new approaches need to be developed that enhance paracellular drug transport by specifically and reversibly modulating tight junctions. In this proposal, we investigate the effect of nanostructured surfaces on the modulation of tight junction permeability and transport of key therapeutic molecules in vitro. We seek to determine the mechanisms through which epithelial permeability is enhanced by nanotopography and optimize nanostructured materials to broaden the types of drugs that can be delivered paracellularly. It is expected that the fundamental knowledge gained in these studies will enhance the development of new epithelial drug delivery systems.